5
Amplifiers & Preamplifiers
POWER SUPPLY CONSIDERATIONS
The total current available from the +12V and STATUS terminals on the EXP9 to power keypads, infrared
receivers, switching devices, etc., is 1.8 A. In addition, each of the zone STATUS terminals have a current
limit of 90 mA each max. These currents are enough to power all but the most unusual installations.
However, if you have a system where the total current demand exceeds 1.8 A, then an external power
supply(s) must be used to power the extra devices to prevent overheating and shutdown of the
EXP9.
The following list shows the current required by Xantech devices typically used with EXP9's (and ZPR68-
10's) in multi-zone systems:
DEVICE
CURRENT DEMAND
IR Receiver Models
291-10, 480 series, 490/495 series, 780-10
10 mA
291P, 291-455, 780P, 780-455(hi-frequency types)
15 mA
291-80, 780-80 (CFL types)
20 mA
780-80 CFL Status LED
10 mA
Chart continued on next page
DEVICE
CURRENT DEMAND
Keypad Models
730 Smart Pad
65 mA
Smart Pad
2
(PM1, LM1, WPK series)
85 mA
Smart Pad
2
Status line (PM1, LM1 & WPK series)
5 mA
Models With Control Inputs
PA640 Six Channel Power Amplifier
11 mA
599 Pulsed Switching Module
11 mA
CC12 and SR21 Relay Modules
1 mA
Procedure
Add up the current demands for the devices used in the system. If the total current exceeds 1.8 A, it is then
necessary to use a 782-00 power supply to separately power the V or +12V terminals of the additional
devices that cause the over-current condition. See typical connection diagram, Fig. 5.
Note: The STATUS or Control Inputs of the devices must remain connected to the respective zone
STATUS terminals on the EXP9, where used. Also, if you exceed 90 mA on any one of the STATUS
terminals, use a Xantech CC12 Remote Relay Module to reduce the current demand. Refer to the CC12
Installation Instructions, Fig. 6, for details.
Example 1
Four Smart Pad
2
's (with Status) and five 780-80's (with Status), are connected to the zones on the EXP9.
Add up the currents: (4 x 90 mA) + (5 x 30 mA) = 510 mA total. This is well within the 1.8 A (1800 mA) limit.
Therefore, no external power supply is needed.
Example 2
24 Smart Pad
2
's (2 in some zones, 3 in others, with Status) and eighteen 780-80's (2 per zone, with Status),
are connected to the zones on the EXP9. Add up the currents: (24 x 90 mA) + (18 x 30 mA) = 2700 mA total
current. This exceeds the 1.8 A limit by 900 mA. Therefore, a 782-00 external power supply is needed
to power the extra Smart Pad
2
's and IR receivers that cause the 1.8 A limit to be exceeded. In this case,
you could power eleven Smart Pad
2
's externally (11 x 85 mA = 935 mA) to ease the load sufficiently.
EXP9
